Investment Securities: Narrative (Details)	12 Months Ended
	Sep. 30, 2024 USD ($) security	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($) security
Schedule of Held-to-maturity and Available-for-sale Securities [Line Items]
Loss on sale of securities	$ 2,000	$ 11,000	$ 1,000
Held-to-maturity securities, realized loss, number of securities | security	14	14	16
Gain on sale of investments		$ 95,000
ACL	$ 60,000	0
Accrued interest on held-to-maturity securites	455,000
Asset Pledged as Collateral
Schedule of Held-to-maturity and Available-for-sale Securities [Line Items]
Security owned and pledged as collateral	208,810,000	201,820,000
Private label residential
Schedule of Held-to-maturity and Available-for-sale Securities [Line Items]
ACL	55,000	$ 0
Held-to-maturity securities in non-accrual status	$ 51,000